Method for cleaning a particular filter

ABSTRACT

The invention relates to a method of cleaning a particle filter ( 1 ) by means of a fluid, whereby the filter material is alternately treated with pressure and high flow rate. By means of the above method, the ash is washed out of the filter material, essentially more effectively, namely quicker and more completely and more gently for the filter material ( 2 ) than previously possible.

SPECIFICATION

[0001] This invention relates to a method for cleaning a particle filter in the exhaust system of an internal combustion engine, in particular an auto-ignition internal combustion engine, the particle filter having a filter housing into which there is inserted filter material through which the exhaust can flow, (soot) particles and ashes separated from the exhaust adhering to the filter material, and the ashes arising being flushable as necessary by liquid conveyable through the filter material.

[0002] Such a method is known from DE 43 13 132 C2. The particle filter described in this document, in the exhaust system of a diesel engine, is cleaned in that the soot particles emplaced in the filter material are burned off and the filter material is then rinsed with a liquid, which is in particular an aqueous solvent with additives. Rinsing is effected in countercurrent to the exhaust stream. For this purpose the aqueous solution is either delivered continuously by a pump or drawn from a liquid reservoir lying geodetically higher than the particle filter. Cleaning is effected by first completely flooding the filter material by closing the drain for the aqueous solution, then waiting until the ash has dissolved out of the filter material, and finally opening the drain and allowing the aqueous solution together with the dissolved ash to be removed from the filter material. The filter material can be dried with compressed air afterward.

[0003] It is an object of the invention to identify a method for cleaning inorganic residues from a particle filter, which method is effective and easy to apply.

[0004] This object is achieved in that the filter material is acted upon by turns with pressure and high flow velocity. By this method the ashes and also at least partially the (soot) particles are flushed from the filter material in a way that is much more effective, that is, more rapid, complete and gentle to the filter material, than was formerly possible. With regard to the method according to the invention it does not matter how and where the ashes have arisen. Naturally, they may have arisen by chemical reactions of substances stored in the filter material, but likewise they may have been formed inside the internal combustion engine by reactions of substances contained in the fuel and in the lubricating oil. In a first variant, the filter material is acted upon by a two-phase flow of the liquid. The liquid is thus conveyed through the filter material in its liquid phase and its gas phase. Because, as will be exhibited later, the liquid is advantageously heated to a temperature in the range of the boiling point anyway, the institution of the gas and of the liquid phase of the liquid imposes no substantial expenditure. The gas phase can be instituted, for example, in that after heating of the liquid to a temperature in the range of the boiling point, part of the liquid is withdrawn and converted into its vapor state, for example in a separate vessel or part of a vessel. In a second variant, a gas and the liquid flow through the filter material alternately. In further development, water vapor, air or exhaust of the internal combustion engine, which is running during the cleaning operation, is advantageously used as gas. Naturally, other gases can also be employed, but the gases concretely named above have proven suitable here on account of their availability. Both variants are consequently easy to apply, and in particular the particle filter need not be removed from the exhaust tract.

[0005] In development of the invention, tap water is used as liquid. Detergents and in particular environmentally compatible substances are admixed with the tap water as necessary. This can be effected by generating a corresponding mixture in a corresponding feed vessel or, however, also by metered addition while the tap water is being conveyed through the filter material.

[0006] In further development of the invention, the temperature of the liquid while working on the filter material is adjusted to approximately 60 to 100° C. The temperature is adjusted in particular in dependence on the instantaneous temperature in the filter material. If for example the temperature in the filter material before or at the beginning of the cleaning operation is higher than 100° C., the liquid is admitted at a low temperature (for example 60° C.) in order to cool the filter material. If the filter material has a temperature of less than 100° C. at the beginning of the cleaning operation, the liquid can be admitted into the filter material in vapor form in order to generate the liquid phase favorable for the cleaning operation through condensation inside the filter material.

[0007] In development of the invention, the fluctuations of pressure and flow velocity are generated by pulsation of the gas and/or by pulsating admission of the liquid. This can be effected for example through pulsewise actuated valves in the supply line or lines or, however, through correspondingly pulsewise actuated pumps or compressors.

[0008] In development of the invention, the liquid and/or the gas is conveyed through the filter material in countercurrent to the exhaust stream. This is the preferred embodiment, a cocurrent direction of flow also being possible, however.

[0009] In further development of the invention, the backwashed (soot) particles together with the cleaning agents can escape through a cleaning opening upstream of the particle filter. In further development, the internal combustion engine is in service during this cleaning operation, the exhausts of the internal combustion engine likewise being able to escape through the cleaning opening upstream of the particle filter. This embodiment is preferably performed during a shop cleaning operation in the built-in state. Thus by this development water or ash sludge is prevented from reaching the internal combustion engine or sensitive sensors in the exhaust system. It is also conceivable to employ the exhaust as the gaseous substance of the cleaning combination in this process.

[0010] In development of the invention, the flushed ash is separated from the liquid and collected in a downstream separator, for example in a liquid separator. The liquid is thus available at least for further flushing operations, while the ash is removed from the liquid separator and forwarded to disposal.

[0011] Depending on the service of the internal combustion engine and the size of the particle filter or of the cleaning device, cleaning is effected in the context of a shop visit or in normal operation or onsite during an operational halt of the internal combustion engine.

[0012] Further advantageous embodiments of the invention can be inferred from the description of the Drawings, in which an example depicted in the FIGURE is described in more detail.

[0013] The single FIGURE shows a particle filter housing 1 into which filter material 2 is inserted. Filter housing 1 is fashioned in the shape of a circular cylinder and has annular end pieces 3 a, 3 b. Opening into these end pieces 3 a, 3 b is an exhaust inlet line 4 a and an exhaust outlet line 4 b. Exhaust inlet line 4 a is connected to the internal combustion engine in suitable fashion, while exhaust outlet line 4 b opens into the environment. Naturally, still further noise suppressors and/or cleaning devices or exhaust bypasses or exhaust short-circuit lines can be inserted into exhaust inlet line 4 a and exhaust outlet line 4 b.

[0014] During the operation of the internal combustion engine, (soot) particles and ashes are filtered out of the exhaust in filter material 1. These particles are made up for the most part of soot and organic residues. A variety of methods (so-called regeneration methods) are available for the continous or discontinuous elimination of these substances from particle filters, these methods being performed in time-dependent or operation-dependent fashion. For example, the particles built up in filter material 2 can be converted at least largely to ashes by combustion or chemical processes. The particles emitted from internal combustion engines also, however, contain inorganic constituents, chiefly oxidation products of organometal additives to lubricating oil and to fuel, as well as wear products. These substances (ashes) cannot be eliminated by conventional methods. These ashes are removed by flushing of filter material 2. For this purpose at least one liquid flows through the filter material, which liquid is conveyed through filter material 2 under pressure and at high flow velocity by turns. For this purpose at least two further ports 5 a, 5 b are arranged in end pieces 3 a, 3 b, through which ports the liquid is led into filter housing 1 and led out again. The liquid is conveyed through filter housing 1 in countercurrent to the exhaust stream or with the exhaust stream. In the first case, a check valve 6 can be inserted into exhaust inlet line 4 a, which check valve then closes automatically or by manual actuation. Still further ports 7 a, 7 b can be let into end pieces 3 a, 3 b, through which further ports the liquid is conveyed in a different phase state. It is also provided, however, to lead the liquid, in a different phase state from that in the first phase state, in and out via ports 5 a, 5 b. The liquid is normally water with which detergents are admixed as appropriate, the temperature of the liquid while working on filter material 2 preferably lying at 60 to 100 degrees Celsius, being controlled in dependence on the filter temperature. 

1. A method for cleaning a particle filter in the exhaust system of an internal combustion engine, in particular an auto-ignition internal combustion engine, the particle filter having a filter housing into which there is inserted filter material through which the exhaust can flow, (soot) particles and ashes separated from the exhaust adhering to the filter material, and the ashes arising being flushable as necessary by liquid conveyable through the filter material, wherein the filter material (2) is acted upon by pressure and high flow velocity by turns.
 2. The method of claim 1 wherein the filter material (2) is acted upon by a two-phase flow of the liquid.
 3. The method of claim 1 wherein a gas and the liquid flow through the filter material (2) alternately.
 4. The method of one of the foregoing claims wherein water vapor, air or the exhaust of the internal combustion engine, which is running during the cleaning operation, is used as gas.
 5. The method of one of the foregoing claims wherein tap water is used as liquid.
 6. The method of claim 5 wherein detergents are admixed with the tap water.
 7. The method of claim 5 or 6 wherein the temperature of the liquid while working on the filter material (2) lies at 60 to 100° C.
 8. The method of one of the foregoing claims wherein the fluctuations of pressure and flow velocity are generated by pulsations of the gas stream and/or by pulsating admission of the liquid.
 9. The method of one of the foregoing claims wherein the temperature of the liquid is adjusted in particular in dependence on the temperature in the filter material (2).
 10. The method of one of the foregoing claims wherein the liquid and/or the gas is conveyed through the filter material (2) in countercurrent to the exhaust stream.
 11. The method of claim 10 wherein the backwashed (soot) particles together with the cleaning agents can escape through a cleaning opening upstream of the particle filter.
 12. The method of claim 11 wherein the internal combustion engine is in service during the cleaning operation, the exhausts of the internal combustion engine likewise escaping through the cleaning opening upstream of the particle filter.
 13. The method of one of the foregoing claims wherein the expelled ash is separated from the liquid and collected in a downstream separator.
 14. The method of one of the foregoing claims wherein cleaning is effected in the context of a shop visit.
 15. The method of one of the foregoing claims wherein cleaning is effected during normal service of the internal combustion engine under normal operating conditions or during an operational halt. 